{"gene":"BTAF1","run_date":"2026-06-09T22:02:45","timeline":{"discoveries":[{"year":1992,"finding":"B-TFIID, purified from mammalian cell extracts, consists of two subunits: TBP and a 170 kDa TAF (BTAF1/TAFII170); the highly purified B-TFIID fractions possess (d)ATPase activity.","method":"Biochemical purification, subunit composition analysis, ATPase activity assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct biochemical reconstitution and enzymatic activity measurement on purified native complex, foundational characterization replicated by later studies","pmids":["1387711"],"is_preprint":false},{"year":1994,"finding":"Yeast TAFII170 (Taf170) is encoded by MOT1 and forms a distinct TBP-Taf170 binary complex separate from the multisubunit TFIID complex, establishing it as a bona fide TAF with a unique role in transcriptional regulation.","method":"Protein sequencing of purified TAF, co-fractionation, complex resolution by biochemical methods","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal biochemical methods (purification, sequencing, co-fractionation) establishing identity and complex distinctness; replicated across yeast and mammalian systems","pmids":["8083216"],"is_preprint":false},{"year":1997,"finding":"Recombinant human TAFII170 (BTAF1) has (d)ATPase activity, and co-fractionation/co-precipitation experiments confirmed it is the TAF subunit of B-TFIID. Its primary structure shows homology to yeast MOT1 and Drosophila moira, consistent with a role as a global regulator of pol II transcription.","method":"cDNA cloning, recombinant protein expression, ATPase assay, co-fractionation, co-precipitation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — recombinant enzyme assay combined with co-precipitation and co-fractionation confirming identity; multiple orthogonal methods in a single rigorous study","pmids":["9342322"],"is_preprint":false},{"year":2001,"finding":"BTAF1 (TAFII170) interacts with TBP via three amino-terminal regions (residues 2–137, 290–381, and 380–460), each containing HEAT repeats; the interaction targets the concave DNA-binding surface of TBP, and region 290–381 inhibits TBP–TATA box complex formation, supporting a mechanism by which BTAF1 induces high-mobility TBP–DNA binding through reversible competition for TBP's concave surface.","method":"Deletion mutagenesis, binding assays with altered-specificity TBP mutant (TBPAS), competitive inhibition assays with TAFII230, TBP-DNA binding assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — active-site mutagenesis of TBP combined with competitive biochemical assays and domain mapping; multiple orthogonal methods in a single study","pmids":["11585931"],"is_preprint":false},{"year":2003,"finding":"BTAF1 (and its yeast ortholog Mot1p) can dissociate TBP from TATA DNA complexes in an ATP hydrolysis-dependent manner, functioning both as a repressor and positive regulator of pol II transcription by dynamically redistributing TBP on promoters.","method":"Review synthesizing genetic and biochemical experiments (ATP-dependent TBP dissociation assays, genetic repressor/activator analyses)","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic conclusions drawn from prior experimental work reviewed comprehensively; no new primary experiments in this review paper, but consolidates replicated findings","pmids":["14557059"],"is_preprint":false},{"year":2004,"finding":"NC2alpha (DRAP1) physically interacts with BTAF1 and stimulates BTAF1's ATP-dependent association with TBP; NC2beta does not associate with BTAF1 and interferes with the BTAF1–TBP interaction. The stimulatory effect of NC2alpha does not require BTAF1's ATPase activity or phosphorylation of NC2alpha.","method":"Co-immunoprecipitation, cell extract binding assays with ATP, ATPase-deficient BTAF1 mutants, domain-specific interaction experiments","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP and mutant analysis from a single lab with multiple orthogonal methods; mechanistic dissection of NC2alpha vs NC2beta contributions","pmids":["15509807"],"is_preprint":false},{"year":2004,"finding":"Electron microscopy single-particle analysis of native and recombinant B-TFIID determined its molecular architecture at 28 Å resolution: a 15×9 nm structure with a large ~170 kDa domain subdivided into two subdomains and a protruding thumb. Immunolabeling localized the C-terminus of BTAF1 in the 170-kDa domain, the N-terminus and TBP at the end of the thumb, and the central portion of BTAF1 at the base of the thumb.","method":"Electron microscopy, single-particle image analysis, immunolabeling with antibodies against BTAF1 termini and TBP","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — structural determination by EM with immunolabeling for functional domain mapping; native and recombinant complexes compared with consistent results","pmids":["14988402"],"is_preprint":false},{"year":2000,"finding":"The human BTAF1 (TAFII170) gene contains 37 introns, lacks a canonical TATA box and initiator element at its promoter, maps to chromosome 10q22-q23, and a 264 bp promoter fragment is sufficient to direct transcription as shown by deletion analysis.","method":"Genomic cloning, ribonuclease-protection assays, promoter deletion analysis, chromosomal mapping by two independent methods","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional promoter deletion assay combined with chromosomal mapping; structural gene characterization with defined minimal promoter","pmids":["10642510"],"is_preprint":false}],"current_model":"BTAF1 (TAFII170/TAF-172) is an SNF2-like ATPase that forms the two-subunit B-TFIID complex with TBP; its N-terminal HEAT-repeat-containing regions interact with the concave DNA-binding surface of TBP, competitively inhibiting TBP–TATA box binding and enabling ATP-dependent dissociation of TBP from promoter DNA, thereby dynamically regulating TBP availability and RNA polymerase II transcription both positively and negatively, with its activity further modulated by physical interaction with NC2alpha."},"narrative":{"mechanistic_narrative":"BTAF1 (TAFII170/TAF-172) is an ATP-dependent regulator of TBP that governs RNA polymerase II transcription by controlling the availability of TBP on promoter DNA [PMID:1387711, PMID:14557059]. It is the 170 kDa TAF subunit of the two-subunit B-TFIID complex, which it forms with TBP and which carries intrinsic (d)ATPase activity [PMID:1387711, PMID:9342322]; recombinant BTAF1 reconstitutes this enzymatic activity and is the orthologue of yeast MOT1 and Drosophila moira, marking it as a global transcriptional regulator [PMID:8083216, PMID:9342322]. BTAF1 engages TBP through three amino-terminal HEAT-repeat regions that target the concave DNA-binding surface of TBP, and one of these regions (residues 290–381) competitively inhibits TBP–TATA box complex formation, providing the structural basis for reversible occupancy of TBP's DNA-binding face [PMID:11585931]. Using ATP hydrolysis, BTAF1 dissociates TBP from TATA DNA, dynamically redistributing TBP on promoters and thereby acting as both a repressor and a positive regulator of pol II transcription [PMID:14557059]. This activity is modulated by NC2alpha (DRAP1), which physically interacts with BTAF1 and stimulates its ATP-dependent association with TBP independently of BTAF1 ATPase activity, whereas NC2beta does not bind and instead interferes with the BTAF1–TBP interaction [PMID:15509807]. Single-particle electron microscopy resolved the B-TFIID architecture, placing the BTAF1 C-terminus in the large 170 kDa domain and the BTAF1 N-terminus together with TBP at the tip of a protruding thumb [PMID:14988402].","teleology":[{"year":1992,"claim":"Established that a distinct TBP-containing complex, B-TFIID, exists as a two-subunit assembly with enzymatic activity, defining BTAF1 as a novel 170 kDa TAF rather than part of canonical TFIID.","evidence":"Biochemical purification of B-TFIID from mammalian extracts with subunit composition and ATPase assays","pmids":["1387711"],"confidence":"High","gaps":["Did not assign the ATPase activity to a specific subunit","No sequence or domain identity for the 170 kDa TAF"]},{"year":1994,"claim":"Identified the yeast counterpart as MOT1-encoded Taf170 forming a binary TBP complex separate from TFIID, anchoring BTAF1 in a conserved regulatory framework.","evidence":"Protein sequencing, co-fractionation, and complex resolution in yeast","pmids":["8083216"],"confidence":"High","gaps":["Mechanism by which the binary complex regulates transcription not resolved here","Human orthologue not yet cloned"]},{"year":2000,"claim":"Characterized the human BTAF1 gene structure and minimal promoter, providing genomic context for the transcript.","evidence":"Genomic cloning, ribonuclease-protection, promoter deletion analysis, and chromosomal mapping","pmids":["10642510"],"confidence":"Medium","gaps":["No functional consequence of promoter elements on BTAF1 expression in vivo","Regulatory inputs to the TATA-less promoter unknown"]},{"year":1997,"claim":"Cloned human BTAF1 and demonstrated that the recombinant protein itself carries the (d)ATPase activity and is the TAF subunit of B-TFIID, with homology marking it as a global pol II regulator.","evidence":"cDNA cloning, recombinant expression, ATPase assays, co-fractionation and co-precipitation","pmids":["9342322"],"confidence":"High","gaps":["Substrate or function of the ATPase activity not yet defined","No domain mapping of the TBP interaction"]},{"year":2001,"claim":"Mapped the TBP-binding determinants to three N-terminal HEAT-repeat regions targeting TBP's concave DNA-binding surface, explaining how BTAF1 competes with TATA-box binding.","evidence":"Deletion mutagenesis, altered-specificity TBP mutant binding, and competitive TBP-DNA binding assays","pmids":["11585931"],"confidence":"High","gaps":["Did not directly demonstrate ATP-dependent dissociation in this study","Contribution of each region to full-length function not quantified"]},{"year":2004,"claim":"Resolved the B-TFIID molecular architecture and positioned BTAF1 termini and TBP within the structure, linking domain organization to function.","evidence":"Single-particle electron microscopy with immunolabeling of native and recombinant complexes","pmids":["14988402"],"confidence":"High","gaps":["No atomic-resolution structure of the BTAF1–TBP interface","DNA-bound or ATP-bound conformational states not captured"]},{"year":2004,"claim":"Defined NC2alpha (DRAP1) as a positive modulator that stimulates BTAF1–TBP association, while NC2beta antagonizes it, adding a regulatory layer to BTAF1 function.","evidence":"Reciprocal co-immunoprecipitation, ATP-dependent binding assays, and ATPase-deficient BTAF1 mutants","pmids":["15509807"],"confidence":"Medium","gaps":["Functional transcriptional consequence of NC2alpha stimulation not demonstrated on promoters","Single-lab data without reciprocal cross-validation in other systems"]},{"year":null,"claim":"How BTAF1-mediated TBP redistribution is targeted to specific promoters genome-wide and integrated with other transcription regulators remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No genome-wide promoter occupancy mapping in the corpus","Physiological gene targets of BTAF1 regulation not defined","No atomic structure of the ATP-driven TBP dissociation reaction"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,2]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,2,4]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[3,4]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,4]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3,4]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,4]}],"complexes":["B-TFIID"],"partners":["TBP","DRAP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O14981","full_name":"TATA-binding protein-associated factor 172","aliases":["ATP-dependent helicase BTAF1","B-TFIID transcription factor-associated 170 kDa subunit","TAF(II)170","TBP-associated factor 172","TAF-172"],"length_aa":1849,"mass_kda":206.9,"function":"Regulates transcription in association with TATA binding protein (TBP). Removes TBP from the TATA box in an ATP-dependent manner","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O14981/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/BTAF1","classification":"Not Classified","n_dependent_lines":499,"n_total_lines":1208,"dependency_fraction":0.41307947019867547},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TBP","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/search/BTAF1","total_profiled":1310},"omim":[{"mim_id":"617725","title":"FUCOSE MUTAROTASE; FUOM","url":"https://www.omim.org/entry/617725"},{"mim_id":"605191","title":"BTAF1 RNA POLYMERASE II, B-TFIID TRANSCRIPTION FACTOR-ASSOCIATED, 170-KD;  BTAF1","url":"https://www.omim.org/entry/605191"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/BTAF1"},"hgnc":{"alias_symbol":["TAFII170","TAF172","MOT1","TAF-172","TAF(II)170"],"prev_symbol":[]},"alphafold":{"accession":"O14981","domains":[{"cath_id":"1.25.10","chopping":"2-75","consensus_level":"medium","plddt":80.9214,"start":2,"end":75},{"cath_id":"1.25.10,1.25.40","chopping":"515-631_656-761","consensus_level":"medium","plddt":85.7444,"start":515,"end":761},{"cath_id":"-","chopping":"769-863","consensus_level":"medium","plddt":86.3145,"start":769,"end":863},{"cath_id":"3.40.50.10810","chopping":"1250-1508","consensus_level":"high","plddt":82.4451,"start":1250,"end":1508},{"cath_id":"1.25.10","chopping":"1056-1228","consensus_level":"medium","plddt":84.7565,"start":1056,"end":1228}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O14981","model_url":"https://alphafold.ebi.ac.uk/files/AF-O14981-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O14981-F1-predicted_aligned_error_v6.png","plddt_mean":75.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=BTAF1","jax_strain_url":"https://www.jax.org/strain/search?query=BTAF1"},"sequence":{"accession":"O14981","fasta_url":"https://rest.uniprot.org/uniprotkb/O14981.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O14981/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O14981"}},"corpus_meta":[{"pmid":"8083216","id":"PMC_8083216","title":"Yeast Taf170 is encoded by MOT1 and exists in a TATA box-binding protein (TBP)-TBP-associated factor complex distinct from transcription factor IID.","date":"1994","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/8083216","citation_count":78,"is_preprint":false},{"pmid":"1387711","id":"PMC_1387711","title":"Composition of transcription factor B-TFIID.","date":"1992","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/1387711","citation_count":77,"is_preprint":false},{"pmid":"14557059","id":"PMC_14557059","title":"Roles for BTAF1 and Mot1p in dynamics of TATA-binding protein and regulation of RNA polymerase II transcription.","date":"2003","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/14557059","citation_count":46,"is_preprint":false},{"pmid":"9342322","id":"PMC_9342322","title":"Cloning of the cDNA for the TATA-binding protein-associated factorII170 subunit of transcription factor B-TFIID reveals homology to global transcription regulators in yeast and Drosophila.","date":"1997","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9342322","citation_count":41,"is_preprint":false},{"pmid":"11585931","id":"PMC_11585931","title":"TAF(II)170 interacts with the concave surface of TATA-binding protein to inhibit its DNA binding activity.","date":"2001","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11585931","citation_count":30,"is_preprint":false},{"pmid":"15509807","id":"PMC_15509807","title":"NC2alpha interacts with BTAF1 and stimulates its ATP-dependent association with TATA-binding protein.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15509807","citation_count":25,"is_preprint":false},{"pmid":"14550797","id":"PMC_14550797","title":"Polyhomeotic stably associates with molecular chaperones Hsc4 and Droj2 in Drosophila Kc1 cells.","date":"2003","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/14550797","citation_count":16,"is_preprint":false},{"pmid":"14988402","id":"PMC_14988402","title":"Molecular architecture of the basal transcription factor B-TFIID.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14988402","citation_count":10,"is_preprint":false},{"pmid":"10642510","id":"PMC_10642510","title":"The gene for human TATA-binding-protein-associated factor (TAFII) 170: structure, promoter and chromosomal localization.","date":"2000","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/10642510","citation_count":5,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":5825,"output_tokens":2053,"usd":0.024135,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9017,"output_tokens":2599,"usd":0.05503,"stage2_stop_reason":"end_turn"},"total_usd":0.079165,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1992,\n      \"finding\": \"B-TFIID, purified from mammalian cell extracts, consists of two subunits: TBP and a 170 kDa TAF (BTAF1/TAFII170); the highly purified B-TFIID fractions possess (d)ATPase activity.\",\n      \"method\": \"Biochemical purification, subunit composition analysis, ATPase activity assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct biochemical reconstitution and enzymatic activity measurement on purified native complex, foundational characterization replicated by later studies\",\n      \"pmids\": [\"1387711\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Yeast TAFII170 (Taf170) is encoded by MOT1 and forms a distinct TBP-Taf170 binary complex separate from the multisubunit TFIID complex, establishing it as a bona fide TAF with a unique role in transcriptional regulation.\",\n      \"method\": \"Protein sequencing of purified TAF, co-fractionation, complex resolution by biochemical methods\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal biochemical methods (purification, sequencing, co-fractionation) establishing identity and complex distinctness; replicated across yeast and mammalian systems\",\n      \"pmids\": [\"8083216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Recombinant human TAFII170 (BTAF1) has (d)ATPase activity, and co-fractionation/co-precipitation experiments confirmed it is the TAF subunit of B-TFIID. Its primary structure shows homology to yeast MOT1 and Drosophila moira, consistent with a role as a global regulator of pol II transcription.\",\n      \"method\": \"cDNA cloning, recombinant protein expression, ATPase assay, co-fractionation, co-precipitation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — recombinant enzyme assay combined with co-precipitation and co-fractionation confirming identity; multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"9342322\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"BTAF1 (TAFII170) interacts with TBP via three amino-terminal regions (residues 2–137, 290–381, and 380–460), each containing HEAT repeats; the interaction targets the concave DNA-binding surface of TBP, and region 290–381 inhibits TBP–TATA box complex formation, supporting a mechanism by which BTAF1 induces high-mobility TBP–DNA binding through reversible competition for TBP's concave surface.\",\n      \"method\": \"Deletion mutagenesis, binding assays with altered-specificity TBP mutant (TBPAS), competitive inhibition assays with TAFII230, TBP-DNA binding assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — active-site mutagenesis of TBP combined with competitive biochemical assays and domain mapping; multiple orthogonal methods in a single study\",\n      \"pmids\": [\"11585931\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"BTAF1 (and its yeast ortholog Mot1p) can dissociate TBP from TATA DNA complexes in an ATP hydrolysis-dependent manner, functioning both as a repressor and positive regulator of pol II transcription by dynamically redistributing TBP on promoters.\",\n      \"method\": \"Review synthesizing genetic and biochemical experiments (ATP-dependent TBP dissociation assays, genetic repressor/activator analyses)\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic conclusions drawn from prior experimental work reviewed comprehensively; no new primary experiments in this review paper, but consolidates replicated findings\",\n      \"pmids\": [\"14557059\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"NC2alpha (DRAP1) physically interacts with BTAF1 and stimulates BTAF1's ATP-dependent association with TBP; NC2beta does not associate with BTAF1 and interferes with the BTAF1–TBP interaction. The stimulatory effect of NC2alpha does not require BTAF1's ATPase activity or phosphorylation of NC2alpha.\",\n      \"method\": \"Co-immunoprecipitation, cell extract binding assays with ATP, ATPase-deficient BTAF1 mutants, domain-specific interaction experiments\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP and mutant analysis from a single lab with multiple orthogonal methods; mechanistic dissection of NC2alpha vs NC2beta contributions\",\n      \"pmids\": [\"15509807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Electron microscopy single-particle analysis of native and recombinant B-TFIID determined its molecular architecture at 28 Å resolution: a 15×9 nm structure with a large ~170 kDa domain subdivided into two subdomains and a protruding thumb. Immunolabeling localized the C-terminus of BTAF1 in the 170-kDa domain, the N-terminus and TBP at the end of the thumb, and the central portion of BTAF1 at the base of the thumb.\",\n      \"method\": \"Electron microscopy, single-particle image analysis, immunolabeling with antibodies against BTAF1 termini and TBP\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural determination by EM with immunolabeling for functional domain mapping; native and recombinant complexes compared with consistent results\",\n      \"pmids\": [\"14988402\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The human BTAF1 (TAFII170) gene contains 37 introns, lacks a canonical TATA box and initiator element at its promoter, maps to chromosome 10q22-q23, and a 264 bp promoter fragment is sufficient to direct transcription as shown by deletion analysis.\",\n      \"method\": \"Genomic cloning, ribonuclease-protection assays, promoter deletion analysis, chromosomal mapping by two independent methods\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional promoter deletion assay combined with chromosomal mapping; structural gene characterization with defined minimal promoter\",\n      \"pmids\": [\"10642510\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"BTAF1 (TAFII170/TAF-172) is an SNF2-like ATPase that forms the two-subunit B-TFIID complex with TBP; its N-terminal HEAT-repeat-containing regions interact with the concave DNA-binding surface of TBP, competitively inhibiting TBP–TATA box binding and enabling ATP-dependent dissociation of TBP from promoter DNA, thereby dynamically regulating TBP availability and RNA polymerase II transcription both positively and negatively, with its activity further modulated by physical interaction with NC2alpha.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"BTAF1 (TAFII170/TAF-172) is an ATP-dependent regulator of TBP that governs RNA polymerase II transcription by controlling the availability of TBP on promoter DNA [#0, #4]. It is the 170 kDa TAF subunit of the two-subunit B-TFIID complex, which it forms with TBP and which carries intrinsic (d)ATPase activity [#0, #2]; recombinant BTAF1 reconstitutes this enzymatic activity and is the orthologue of yeast MOT1 and Drosophila moira, marking it as a global transcriptional regulator [#1, #2]. BTAF1 engages TBP through three amino-terminal HEAT-repeat regions that target the concave DNA-binding surface of TBP, and one of these regions (residues 290\\u2013381) competitively inhibits TBP\\u2013TATA box complex formation, providing the structural basis for reversible occupancy of TBP's DNA-binding face [#3]. Using ATP hydrolysis, BTAF1 dissociates TBP from TATA DNA, dynamically redistributing TBP on promoters and thereby acting as both a repressor and a positive regulator of pol II transcription [#4]. This activity is modulated by NC2alpha (DRAP1), which physically interacts with BTAF1 and stimulates its ATP-dependent association with TBP independently of BTAF1 ATPase activity, whereas NC2beta does not bind and instead interferes with the BTAF1\\u2013TBP interaction [#5]. Single-particle electron microscopy resolved the B-TFIID architecture, placing the BTAF1 C-terminus in the large 170 kDa domain and the BTAF1 N-terminus together with TBP at the tip of a protruding thumb [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 1992,\n      \"claim\": \"Established that a distinct TBP-containing complex, B-TFIID, exists as a two-subunit assembly with enzymatic activity, defining BTAF1 as a novel 170 kDa TAF rather than part of canonical TFIID.\",\n      \"evidence\": \"Biochemical purification of B-TFIID from mammalian extracts with subunit composition and ATPase assays\",\n      \"pmids\": [\"1387711\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not assign the ATPase activity to a specific subunit\", \"No sequence or domain identity for the 170 kDa TAF\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Identified the yeast counterpart as MOT1-encoded Taf170 forming a binary TBP complex separate from TFIID, anchoring BTAF1 in a conserved regulatory framework.\",\n      \"evidence\": \"Protein sequencing, co-fractionation, and complex resolution in yeast\",\n      \"pmids\": [\"8083216\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which the binary complex regulates transcription not resolved here\", \"Human orthologue not yet cloned\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Characterized the human BTAF1 gene structure and minimal promoter, providing genomic context for the transcript.\",\n      \"evidence\": \"Genomic cloning, ribonuclease-protection, promoter deletion analysis, and chromosomal mapping\",\n      \"pmids\": [\"10642510\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional consequence of promoter elements on BTAF1 expression in vivo\", \"Regulatory inputs to the TATA-less promoter unknown\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Cloned human BTAF1 and demonstrated that the recombinant protein itself carries the (d)ATPase activity and is the TAF subunit of B-TFIID, with homology marking it as a global pol II regulator.\",\n      \"evidence\": \"cDNA cloning, recombinant expression, ATPase assays, co-fractionation and co-precipitation\",\n      \"pmids\": [\"9342322\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate or function of the ATPase activity not yet defined\", \"No domain mapping of the TBP interaction\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Mapped the TBP-binding determinants to three N-terminal HEAT-repeat regions targeting TBP's concave DNA-binding surface, explaining how BTAF1 competes with TATA-box binding.\",\n      \"evidence\": \"Deletion mutagenesis, altered-specificity TBP mutant binding, and competitive TBP-DNA binding assays\",\n      \"pmids\": [\"11585931\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not directly demonstrate ATP-dependent dissociation in this study\", \"Contribution of each region to full-length function not quantified\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Resolved the B-TFIID molecular architecture and positioned BTAF1 termini and TBP within the structure, linking domain organization to function.\",\n      \"evidence\": \"Single-particle electron microscopy with immunolabeling of native and recombinant complexes\",\n      \"pmids\": [\"14988402\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No atomic-resolution structure of the BTAF1\\u2013TBP interface\", \"DNA-bound or ATP-bound conformational states not captured\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined NC2alpha (DRAP1) as a positive modulator that stimulates BTAF1\\u2013TBP association, while NC2beta antagonizes it, adding a regulatory layer to BTAF1 function.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation, ATP-dependent binding assays, and ATPase-deficient BTAF1 mutants\",\n      \"pmids\": [\"15509807\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional transcriptional consequence of NC2alpha stimulation not demonstrated on promoters\", \"Single-lab data without reciprocal cross-validation in other systems\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How BTAF1-mediated TBP redistribution is targeted to specific promoters genome-wide and integrated with other transcription regulators remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No genome-wide promoter occupancy mapping in the corpus\", \"Physiological gene targets of BTAF1 regulation not defined\", \"No atomic structure of the ATP-driven TBP dissociation reaction\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 2, 4]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [3, 4]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"complexes\": [\"B-TFIID\"],\n    \"partners\": [\"TBP\", \"DRAP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}